Peracid compounds

ABSTRACT

Organic peracids supported on inorganic macromolecular supports and a process for preparing them are provided. The peracids have general chemical formulae: Q--O--Si--A--NR--X--CO 3  H (I) wherein Q represents the inorganic support, A is an alkylene or arylene group, R represents hydrogen, alkyl or an aryl group and X represents an optionally substituted alkylene or arylene group, or Q--O--Si--A--N X&#39;--CO 3  H (II) where Q and A are as defined above, and X&#39; represents an optionally substituted alkylene or arylene group. The peracids have improved stability and recovery characteristics compared with those of the prior art.

BACKGROUND OF THE INVENTION

This invention concerns organic peracids, and more specifically, organicperacids bonded to an inorganic support.

Organic peracids have found many applications throughout industrybecause of their oxidative nature. For example, they are widely employedas oxidants in organic reactions, including use in epoxidationreactions, where certain examples have been found to be useful selectiveoxidants. Examples are also used to disinfect and reduce the chemicaloxygen demand of aqueous effluent streams.

In the majority of applications for peracids, in order for the peracidto have an effect on the desired substrate it has often been foundnecessary for the peracid to be employed as either a solution, or insome other form, for example a powder, which is capable of producing anin-situ solution of the peracid. Once the peracid has acted on thesubstrate, it is often reduced to form the corresponding acid, which hasno further oxidative activity. Such spent reagent can then either bediscarded or can be recovered from the oxidation medium for possiblerecycling or use in other processes. When the peracid is a cheap andreadily produced one such as peracetic acid, it is often acceptable forthe peracid to be discarded, unless there are special circumstancesnecessitating or permitting its easy recovery. However, in many cases,it is desirable that discarding the spent reagent is avoided, ifpossible, because it represents a waste of chemical raw materials andalso adds to process and effluent treatment costs. This is particularlyso in cases where the peracid employed is more complex and/or moreexpensive to produce than simple peracids such as peracetic acid.

One option for reducing the wastage of chemicals is to regenerate theperacid from the acid in the oxidation medium by adding an oxidisingagent. Unfortunately, this approach suffers from the drawback that theconcentration of acid remaining in the oxidation medium is oftenrelatively low. This means that the reaction kinetics and/or equilibriumfor the production of the peracid are unfavourable for a rapid andeconomic reaction to occur.

Another option for reducing chemical wastage is to separate theremaining acid from the reaction medium for conversion back to peracid,or for use in other processes. There are many disadvantages to thiswhere conventional peracids are employed. For example, if both theoxidation product and the spent reagent are solids, purification stagesare necessary. If the spent reagent remains in solution in the oxidationmedium, it may be necessary, for example, to evaporate off the solventuntil the spent reagent precipitates, but even this does not guaranteethe purity of the acid produced and further purification can benecessary. In many cases, such separations require specialised plant,which adds to the cost of the process, as well as increasing the needfor space.

Nevertheless, it remains desirable that the spent reagent should berecoverable from the oxidation medium, preferably by the use of arelatively simple separation process such as filtration. One option toachieve this is to employ the peracid in a form such that the recoveryof the acid could easily be achieved. One possibility that has beenexplored is to physically absorb a peracid on an insoluble support, butthis approach has the problem that the peracid is attached to thesupport by relatively weak intermolecular forces only, so that it isrelatively easy for the peracid or corresponding acid to dissolve andtherefore to be lost from the support.

An alternative approach was suggested by Sherrington et al in EuropeanPolymer Journal Vol 16, pp293-8. Sherrington's process comprisedchemically bonding an aromatic organosilane containing a benzyl chloridemoiety to an inorganic macromolecular support containing pendant hydroxygroups, or modifying an inorganic-supported organic group to include abenzyl chloride moiety. The benzyl chloride moiety was then converted toa benzaldehyde moiety, which was then oxidised to produce a peracid. Thesupported peracids produced by Sherrington's process were found in thestudies leading to the present invention to have poor chemical stabilityand so could not conveniently be stored at ambient temperatures. Thetrials also showed that peracids had a physical form which renderedtheir recovery from the preparative reaction medium by filtrationdifficult, and would also make it difficult to recover and recycle theperacid or corresponding acid when employed as an oxidant.

It is an object of one aspect of the present invention to provideorganic peracids chemically bonded to an inorganic support which haveimproved storage stability and/or superior product recoverycharacteristics compared with those produced by Sherrington.

It is a second objective of another aspect of the present invention toprovide a process for producing organic peracids chemically bonded to aninorganic support which have improved storage stability and/or superiorproduct recovery characteristics compared with those produced bySherrington.

It is a third objective of certain embodiments of the present inventionto provide a process for preparing organic peracids chemically bonded toan inorganic support that employs fewer preparation stages compared withthe process demonstrated by Sherrington.

It is a fourth objective of certain embodiments of the present inventionto provide amido or imido peracids chemically bonded to an inorganicsupport.

SUMMARY OF THE INVENTION

According to the present invention, there are provided organic peracidschemically bonded to an inorganic support, characterised in that theycontain a group either of general chemical formula: ##STR1## where Qrepresents the inorganic support, A is an aliphatic and/or aromaticbridging group, R represents hydrogen, an alkyl or an aryl group, or agroup having the formula X--CO₃ H, X represents an optionallysubstituted alkylene or arylene group and X' represents an optionallysubstituted alkylene or arylene group.

According to a second aspect of the present invention, there is provideda process for producing organic peracids chemically bonded to aninorganic support, characterised in that they contain a group either ofgeneral chemical formula: ##STR2## where Q represents the inorganicsupport, A is an aliphatic and/or aromatic bridging group, R representshydrogen, an alkyl or an aryl group, or a group having the formulaX--CO₃ H, X represents an optionally substituted alkylene or arylenegroup and X' represents an optionally substituted alkylene or arylenegroup comprising the following stages:

Stage (i) Reacting an inorganic support having at least one pendanthydroxy group of formula Q--OH with a silane having the general chemicalformula R'₃ Si--A--NHY, where A is as defined above, R' represents analkoxy group and Y represents hydrogen, alkyl or aryl groups, or a grouphaving the formula X-CO₃ H to form an intermediate of formula ##STR3##

Stage (ii) Reacting the intermediate from Stage (i) with a compound offormula Z--X--D or ZZ'--X'--D where X and X' are as defined above, Z andZ' represent an oxy- or halogen-containing leaving group and Drepresents a carboxylic acid group or a functionality capable ofconversion thereto to form an intermediate of formula ##STR4## and

Stage (iii) Reacting the intermediate from Stage (ii) with hydrogenperoxide in the presence of a strong acid thereby producing aninorganic-supported peracid having one of the general formulae describedabove.

DESCRIPTION OF PREFERRED EMBODIMENTS

The aliphatic and/or aromatic bridging group A in inorganic-supportedperacids according to the present invention can comprise linear orbranched alkylene groups. It can also comprise one or more aromaticrings which may be substituted by one or more alkyl or aryl groups. Inmany preferred embodiments, the bridging group comprises a linearalkylene chain having from 1 to 10 carbon atoms, preferably from 2 to 5carbon atoms. The bridging group can also comprise one or more O or Natoms in place of one or more carbon atoms.

When the inorganic-supported peracids according to the present inventionhave the general chemical formula ##STR5## the group X can be anoptionally substituted alkylene or arylene group, which can include acarbonyl group at the alpha position relative to the N. In certainembodiments, X comprises a linear alkylene chain having up to about 18carbon atoms, preferably from about 10 to about 14 carbon atoms. Inother embodiments, X comprises at least one aromatic ring which may bedirectly bonded to either or both of N and CO₃ H, or may be separatedfrom either or both of them by an alkylene group. In many preferredembodiments, the aromatic ring is bonded directly to the CO₃ H. Thegroup R can be hydrogen or an alkyl or aryl group or a group having theformula X--CO₃ H. When R has the formula X--CO₃ H, the group can eitherbe the same or have a different structure to the other X--CO₃ H in theperacid.

When the inorganic-supported laeracids according to the presentinvention have the general chemical formula ##STR6## the group X' can bean optionally substituted alkylene or arylene group. It will berecognised that the bond between N and X' can comprise a C═N doublebond, but in many embodiments, the bonds between N and X' are such thatthey form a cyclic amino or imido group, preferably having from 5 to 7atoms in the ring. In certain embodiments, the N is bonded to twocarbonyl groups which comprise part of X'. Preferably, the two carbonylgroups are bonded to an aromatic ring. Most preferably, the aromaticring is a benzene ring, and the carbonyl groups are bonded to adjacentcarbons in that ring.

X or X' often comprises up to about 22 carbon atoms, preferably between4 and 16 carbon atoms and most preferably from about 6 to about 10carbon atoms.

The peracid group CO₃ H can be a substituent of any carbon within themolecule X or X'. In many embodiments, the peracid group is separatedfrom N by at least 2 carbon atoms, preferably from about 3 to about 6carbon atoms. In some embodiments, N is bonded to two carbonyl groupswhich are themselves bonded to adjacent carbons in a benzene ring, theperacid group is most preferably bonded directly to the benzene ring inthe meta position relative to one carbonyl group and in the paraposition relative to the other carbonyl. In other embodiments theperacid group is spaced from the benzene ring by an aliphatic group,such as an alkylene group containing from 1 to 6 linear carbons,optionally substituted with an alkyl or aryl substituent. This gives aseparation between N and the peracid group in such embodiments of atleast 4 carbons.

The inorganic support, Q, employed in the present invention can be anyinorganic macromolecule which contains at least one pendant hydroxygroup as such or can be chemically modified to introduce such groups. Inmany embodiments, the inorganic support comprises one or both ofaluminium and silicon based compounds. Silicon-based inorganic supportswhich can be employed to produce the compounds according to the presentinvention include silica gel and diatomaceous earth. Suitable aluminiumbased inorganic supports include alumina. Examples of suitable inorganicsupports including both aluminium and silicon are aluminosilicates,particularly naturally occurring clays such as bentonites, for example,montmorillonite, and synthetic clays such as synthetic hectometers, forexample that available from Laporte Industries Limited under theTrademark "Laponite". It will also be recognised that it is possible toemploy mixtures of different inorganic supports.

The inorganic supports are typically employed as a free-flowing powder.The surface area of the inorganic support is often in the range of fromabout 50 m² /g to about 1000 m² /g, preferably from about 200 m² /g toabout 800 m² /g.

In a particularly preferred embodiment of the present invention, theinorganic support is silica gel having a surface area in the range of250 to 350 m² /g, A is a linear (CH₂)₃ group and N is bonded to twocarbonyl groups fused with a benzene ring to form a phthalimido group,the peracid group being bonded directly to the benzene ring in the metaposition relative to one carbonyl group and in the para positionrelative to the other carbonyl. This gives an inorganic-supportedperacid having the formula: ##STR7##

In the process according to the present invention, it is possible toemploy an inorganic support that contains at least one pendant hydroxygroup without any pre-treatment, but in many cases, it is preferablethat the support is pre-treated in order to increase the numbers ofpendant hydroxy groups and so increase the number of sites for attachingorganic substituents. One convenient pre-treatment is to reflux theinorganic support in a solution of an inorganic acid for about 2 to 6hours. Both dilute or concentrated solutions can be employed. Oneparticularly suitable inorganic acid is hydrochloric acid. After such anacid treatment, the inorganic support is preferably washed free of acidwith water, typically until the pH of the washings reaches 7.

Following any pre-treatment, the inorganic support is often dried. Thiscan be achieved by storing the support under a vacuum of, for exampleless than about 50 mmHg, preferably less than about 10 mmHg, at elevatedtemperature. A typical storage time would be 2 days at a temperature of130° C., although it is possible to envisage faster drying methodsinvolving, for example, higher temperatures.

Stage (i) of the process according to the present invention comprisesreacting the dried inorganic support with a trialkoxysilane. Thetrialkoxysilane is conveniently chosen according to the desiredsupported peracid it is desired to produce. In many cases it ispreferable that the alkoxy groups are low molecular weight alkoxygroups. A particularly suitable silane has been found to beaminopropyltrimethoxysilane, (MeO)₃ Si(CH₂)₃ NH₂, where A=(CH₂)₃. Thisreaction can suitably be achieved by dissolving the silane in a suitableorganic solvent containing a small amount, often up to about 25%,preferably up to about 15%, of the volume of silane employed, of water,and refluxing in the presence of the inorganic support untilsubstantially all of the pendant hydroxy groups has reacted with thesilane. Suitable organic solvents include toluene, hydrocarbons such aspetroleum ethers, halocarbons such as chlorobenzene and ethers, but ispreferably toluene. Typical reaction times do not exceed 24 hours, andin many cases are selected in the range of 3 to 10 hours. Theintermediate from stage (i) can be obtained by suitable separationmeans, for example, filtration or centrifugation, and preferably is thenwashed with a volatile organic solvent to remove substantially all ofany remaining reaction liquor. Suitable volatile organic solventscomprise methanol, ethanol, propanol or acetone. The washed product canthen be dried thoroughly. Preferably, the drying is accomplished undervacuum of, for example less than about 50 mmHg, preferably less thanabout 10 mmHg, at elevated temperatures up to about 90° C. for periodsup to about 72 hours.

Stage (ii) of the process according to the present invention comprisesreacting the intermediate from stage (i) with a suitable compoundcontaining one or two oxy- or halogen-containing leaving groups, Z andZ', and a carboxylic acid group or group capable of conversion thereto,D. It will be recognised that the choice of such a group will often mostconveniently be such that the acid produced in stage (ii) can beperoxidised in stage (iii) to form the desired inorganic supportedperacid, but that this need not necessarily be the case because it ispossible to modify the product of stage (ii) in further stages toproduce the particular compound desired. This will be particularlyconvenient if it is not possible to identify a compound that will reactwith an N--H group to produce the desired molecule in a single stage.Suitable oxy- or halogen-containing leaving groups include ##STR8##groups, particularly --COCl groups, and also anhydride groups.Particularly suitable anhydrides are those of organic diacids where theacid groups are positioned such that the anhydride produced forms acyclic group, for example maleic anhydride or phthalic anhydride. Themost suitable anhydride has been found to be trimellitic anhydride.Typical groups that are capable of conversion to a carboxylic acidcomprise --CH₃ groups, --CHO groups and ester groups.

The reaction between the intermediate produced in stage (i) and thecompound of formula Z--X--D or ZZ'--X'--D conveniently takes place in asuitable solvent, often under reflux conditions. Particularly suitablesolvents are short chain aliphatic acids, particularly acetic acid. Thereaction is preferably continued until substantially all of theintermediate from stage (i) has reacted with the compound of formulaZ--X--D or ZZ'--X'--D. Typical reaction times are unlikely to be longerthan about 24 hours and are preferably from about 2 to 10 hours. Theintermediate from stage (ii) can be obtained by a suitable separationprocess such as filtration or centrifugation, and preferably the productwashed with a volatile organic solvent to remove substantially all ofany remaining reaction liquor. Suitable volatile organic solventscomprise methanol, ethanol, propanol or acetone. The washed product ispreferably then dried thoroughly. Preferably, the drying is accomplishedunder vacuum of, for example less than about 50 mmHg, preferably lessthan about 10 mmHg, at elevated temperatures up to about 90° C. forperiods up to about 72 hours.

It will be recognised that in both stage (i) and (ii), it is possible toemploy the reagents in a wide range of mole ratios includingstoichiometric mole ratios. However, it will also be recognised that inorder to obtain optimum loadings on the inorganic support it can beadvantageous to use a molar excess over the stoichiometric amount of thesilane or compound of formula Z--X--D or ZZ'--X'--D. Any remainingunreacted reagent can usually be removed by washing the inorganicsupport with a suitable solvent, thus avoiding excessive contaminationof the support.

Hereinbefore there has been described a two stage process for producinga compound containing a carboxylic acid, or group capable of conversionthereto, bonded to an inorganic support via a silane in which the firststage comprises bonding the silane to the inorganic support and thesecond stage comprises bonding the compound containing a carboxylicacid, or group capable of conversion thereto, to the silane. In otherembodiments, the reaction sequence can be reversed, whereby in the firststage, the alkoxysilane of formula R'₃ Si--A--NHY is reacted with thecompound of formula Z--X--D or ZZ'--X'--D, and the resultant compound offormula R'₃ Si--A--NR--X--D or ##STR9## is bonded to the inorganicsupport in the second stage. In the first stage of the reverse sequence,the reaction is carried out in a suitable solvent for the compound offormula Z--X--D or ZZ'--X'--D but which does not adversely effect thealkoxysilane. Examples of suitable solvents include non-carboxylic acidsolvents, such as dimethylformamide, and alcohols. When an alcohol isemployed as solvent, it preferably corresponds to the alkoxy groups ofthe silane. Apart from the nature of the solvent in the first stage,substantially the same conditions can be employed for respectively thesilane--support and the compound of formula Z--X--D orZZ'--X'--D--silane reactions in the reverse sequence as for stages (i)and (ii) above. This produces the same compound as when thetrialkoxysilane is first reacted with the inorganic support, and whichcan then be peroxidised in stage (iii). These embodiments offer thepossibility of producing the supported peracids in substantially a onepot process.

Stage (iii) of the process according to the present invention comprisesperoxidising the intermediate produced in stage (ii). The peroxidationprocess employed can be substantially any process for the oxidation ofan organic acid to a peracid. In most cases the peroxidation comprisesreacting the acid with hydrogen peroxide in the presence of a strongacid at a temperature not usually greater than about 40° C. The hydrogenperoxide is often employed as a concentrated aqueous solution, typicallycomprising from about 65 to about 95%, preferably from about 70 to about90%, by weight, and comprises about 10 to about 30 volume percent of thetotal stage (iii) reaction mixture. Preferred strong acids comprisesulphuric acid, methanesulphonic acid and phosphoric acid and mixturesthereof. Another possibility is to employ a pre-formed mixture ofhydrogen peroxide and sulphuric acid in which an effective amount ofCaro's acid is present. It is most convenient that the reaction proceedsat ambient temperature, ie about 20°-25° C. The reaction typicallyproceeds until substantially all of the supported organic acid has beenperoxidised to produce a peracid, or until analysis of the reactionmixture indicates that none of the oxidant remains. At this point,further oxidant may be added, or the reaction may be terminated.Typically, the mole ratio of oxidant to supported acid employed in stage(iii) is at least stoichiometric, and can be up to up to 200:1, becauseit is possible that if only a stoichiometric ratio is employed, anyoxidant decomposition that may occur will result in incompleteperoxidation of the desired peracid. Typically, the strong acid isemployed at a concentration of about 40 to 90, preferably about 65 to85, volume percent of the total stage (iii) reaction mixture. In oneparticular embodiment, the intermediate from stage (ii) is peroxidisedby passing a solution of strong acid and hydrogen peroxide down a columncontaining the intermediate. The product of stage (iii) can be obtainedafter quenching the reaction in an ice/water mixture by a suitableseparation process, eg filtration or centrifugation, and is convenientlyvacuum or air dried at room temperature (20°-25° C.) until no furtherweight loss occurs, indicating that drying is substantially complete.

The process according to the present invention can be operated as eithera batch or continuous process.

The inorganic-supported peracids according to the present invention aresuitable for application as oxidants in a wide range of areas, althoughit will be recognised that the area of application will depend on, forexample, the nature of the peracid on the inorganic support. In manycases, the inorganic supported peracids according to the presentinvention are suitable for similar applications to non-supportedperacids. For example, they are suitable for application asdisinfectants, bleaching agents, waste water treatment agents and asoxidants in synthetic reactions, including use as epoxidising agents.The excellent stability of the peracids according to the presentinvention at ambient temperatures means that they can be storedconveniently, and it is not necessary to prepare the peracidsimmediately prior to use if no suitable refrigerated storage isavailable.

Because of the bonding to the inorganic support, it is most likely thatin the majority of applications, the peracids will function asheterogeneous oxidants. This means that when the oxidation is completed,or the oxidative capacity of the peracids is exhausted, it is very easyto separate the peracid or acid from the oxidising medium by a simpleseparation technique such as filtration. After suitable washing anddrying, if desired, the peracid can then either be employed in anotheroxidising application if it retains any oxidative capacity, or, if theperacid has been reduced to the corresponding acid, it can be oxidisedby a process according to stage (iii) of the present invention tore-generate the peracid. This is a very important feature of theperacids according to the present invention because it allows theefficient recycling of potentially expensive chemicals. In oneparticular embodiment, the peracid is re-generated by passing a solutionof strong acid and hydrogen peroxide down a column containing theinorganic supported acid.

Having described the invention in general terms, specific embodimentswill now be described by way of example only.

EXAMPLE 1. PREPARATION OF PROPYLIMIDOPERMELLITIC ACID SUPPORTED ONSILICA GEL.

Pre-Treatment

100 g of silica gel having a surface area of 300 m² /g was refluxed in350 ml of 2N hydrochloric acid for 4 hours, then cooled, filtered off,washed with demineralised water (DMW) until the pH of the washings waspH 7, washed with acetone and then dried at 130° C.

Stage (i)

50 g of the dried silica gel from the pre-treatment was added to 700 mlof toluene and 25 ml DMW. This mixture was then azeotroped to removewater until no more water was being removed and cooled to roomtemperature. 5 ml DMW was added and the mixture stirred at roomtemperature for 30 minutes. 50 mls aminopropyltrimethoxysilane wasadded, the mixture refluxed for 3 hours, cooled and the functionalisedsilica filtered off, washed with 50 ml toluene then by soxhletextraction with 800 ml methanol for 21 hours and then dried at 80° C.under a vacuum of <6 mmHg.

Stage (ii)

30 g of the functionalised silica from stage (i) above, 30 g trimelliticanhydride and 300 g acetic acid were refluxed for 6 hours, and allowedto stand for 18 hours during which time cooling to room temperatureoccurred. The silica-supported acid was filtered off, washed by soxhletextraction with methanol for 21 hours and dried at 80° C. under a vacuumof <6 mmHg.

Stage (iii)

10 g of the silica-supported acid from stage (ii) above and 8 mlmethanesulphonic acid were stirred at room temperature. 2 ml of an 85%w/w aqueous solution of hydrogen peroxide was added over 1.5 hours, thereaction mixture was allowed to stand for 17 hours, and then quenchedwith ice. The silica-supported peracid was obtained by vacuum filtrationfor about 15 minutes as a white granular solid, washed with ice/wateruntil the pH of the washings reached pH3 to 5, and vacuum dried over P₂O₅.

Analysis of the product of stage (iii) above showed the product tocontain an Available oxygen (avox) content of 0.8% by weight. After 12weeks storage at 32° C., 42% of the initial avox remained.

EXAMPLE 2--USE OF VACUUM DRYING OF SUPPORTED PERACID

The procedure of Example 1 above was followed, except that air dryingwas employed at each stage to give a product having an initial Avox of0.52% by weight with 30% of the initial avox remaining after 12 weeksstorage at 32° C.

EXAMPLE 3--USE OF MONTMORILLONITE AS INORGANIC SUPPORT

The procedure of Example 1 above was followed, except employingmontmorillonite having a surface area of 220-270 m² /g as the inorganicsupport. This gave a supported peracid having an initial avox of 0.33%by weight with 42% of the initial avox remaining after 8 weeks storageat 32° C.

EXAMPLE 4--USE OF CONCENTRATED ACID IN PRE-TREATMENT

The procedure of Example 1 above was followed except that thepre-treatment employed 350 ml of 36% w/w hydrochloric acid solution.This gave a supported peracid having an initial avox of 0.5% by weight.

EXAMPLE 5--NO AZEOTROPE EMPLOYED

The procedure of Example 1 above was followed, except that in stage (i),50 g of silica was dispersed in 200 ml toluene with no addition of 25 mlDMW or azeotroping, and only 10 ml of aminopropyltrimethoxysilane wasemployed. This gave a supported peracid having an initial avox of 0.33%by weight.

EXAMPLE 6--USE OF SILICA GEL HAVING A SURFACE AREA OF 675 m² /g

The procedure of Example 1 above was followed, except that silica gelwith a surface area of 675 m² /g was employed. This gave a supportedperacid having an initial avox of 0.32% by weight.

EXAMPLE 7--USE OF SILICA GEL HAVING A SURFACE AREA OF 480 m² /g

The procedure of Example 1 above was followed, except that silica gelwith a surface area of 480 m² /g was employed. This gave a supportedperacid having an initial avox of 0.67% by weight with 46% of theinitial avox remaining after 8 weeks storage at 32° C.

COMPARISON PREPARATION OF PRIOR ART INORGANIC SUPPORTED PERACID

The method described by Sherrington et al in European Polymer JournalVol 16, p294 was followed, except that for reasons of chemicalavailability, the silane employed was Cl₃ SiCH₂ CH₂ --Ph--CH₂ Cl toproduce the product 4b in column 2 directly. On completion of theprocess according to Sherrington et al, the supported peracid wasobtained by vacuum filtration. The filtration took greater than 2 hoursto complete, and gave a yellow product having an avox of 0.29% byweight. Only 27% of the initial avox remained after 4 weeks storage at32° C.

The results of Examples 1 to 7 show that the inorganic-supportedperacids, according to the present invention have superior stabilitycompared with those according to the prior art, and that the processaccording to the present invention produces inorganic supported peracidshaving superior handling characteristics compared with the prior artprocess.

EXAMPLE 8. USE OF INORGANIC SUPPORTED PERACID IN EPOXIDATION

1 g of cyclohexene, 40 cm³ of dichloromethane and 3.07 g of the productof Example 1 above were stirred in a glass reactor fitted with acondenser for 3 hours at 25° C. The solution was then washed with 10%sodium sulphite solution until no peroxide remained as evidenced by anegative starch test, and then washed with 5% sodium bicarbonatesolution. The inorganic-supported acid remaining was recovered byfiltration. The dichloromethane layer was then separated and analysed byGas Chromatography. The analysis showed that substantially nocyclohexene remained, and that the only product was cyclohexene epoxide.

This result demonstrates that supported peracids according to thepresent invention can be used as oxidants in chemical synthesis, andthat it is very easy to recover the supported peracid or acid oncompletion of the reaction.

EXAMPLE 9. PRODUCTION OF INORGANIC SUPPORTED PERACID USING A COLUMN

A 10 g sample of inorganic supported acid produced according to thepre-treatment and stages (i) and (ii) of Example 1 above was placed in ajacketed glass column. A solution consisting of 80 mls methanesulphonicacid to which 20 mls of aqueous 85% w/w hydrogen peroxide solution hadbeen added over 1 hour was circulated through the column for 17 hours atroom temperature. Cooling water was then applied to the jacket, and thesilica-supported peracid washed with ice/water until the eluent had a pHof 3 to 5. The silica-supported peracid was then vacuum dried as perExample 1.

This gave a supported peracid having an initial avox of 0.44% by weightwith 41% of the initial avox remaining after 4 weeks storage at 32° C.

We claim:
 1. Organic peracids chemically bonded to an inorganic support,characterised in that they contain a group either of general chemicalformula: ##STR10## where Q represents the inorganic support, A is analiphatic and/or aromatic bridging group, R represents hydrogen, analkyl or an aryl group, or a group having the formula X--CO₃ H, Xrepresents an alkylene or arylene group and X' represents an alkylene orarylene group.
 2. The organic peracid according to claim 1, wherein Acomprises a linear alkylene group having from 1 to 10 carbon atoms. 3.The organic peracid according to claim 2, wherein A comprises a linearalkylene group having from 2 to 5 carbon atoms.
 4. An organic peracidaccording to claim 1, wherein X comprises a linear alkylene group havingup to 18 carbon atoms.
 5. The organic peracid according to claim 4,wherein X comprises a linear alkylene group having from 10 to 14 carbonatoms.
 6. An organic peracid according to claims 1, 2, 3, 4 or 5,wherein N--X comprises an amino alkylene or amino arylene group and##STR11## comprises a cyclic imido arylene group.
 7. An organic peracidaccording to claim 6, wherein ##STR12## comprises a phthalimido group.8. The organic peracid according to claim 1, wherein Q comprises analuminum, silicon or aluminosilicate based inorganic support.
 9. Theorganic peracid according to claim 1, wherein Q comprises silica gel ora natural or synthetic clay.
 10. The organic peracid according to claims1, 2, 3, 4, 5, 8 or 9, wherein the inorganic support has a surface areain the range of from about 50 m² /g to about 1000 m² /g.
 11. The organicperacid according to claim 10, wherein the inorganic support has asurface area in the range of from about 200 m² /g to about 800 m² /g.12. The organic peracid according to claim 1, 8, or 9, wherein theinorganic support comprises silica gel having a surface area in therange of 250 to 350 m² /g, A is a linear (CH₂)₃ group and N is bonded totwo carbonyl groups fused with a benzene ring to form a phthalimidogroup, the peracid group being bonded directly to the benzene ring inthe meta position relative to one carbonyl group and in the paraposition relative to the other carbonyl to produce aninorganic-supported peracid having the formula: ##STR13##
 13. Theorganic peracid according to claim 1 wherein X or X' is oxo-substitutedat the alpha position relative to the N.
 14. The organic peracidaccording to claim 1 wherein X or X' separate the peracid group CO₃ Hfrom N by from 2 to 6 carbon atoms.
 15. A process of producing organicperacids chemically bonded to an inorganic support, characterised inthat they contain a group either of general chemical formula: ##STR14##where Q represents the inorganic support, A is an aliphatic and/oraromatic bridging group, R represents hydrogen, an alkyl or an arylgroup, or a group having the formula X--CO₃ H, X represents an alkyleneor arylene group and X' represents an alkylene or arylene groupcomprising the following stages:Stage (i) Reacting an inorganic supporthaving at least one pendant hydroxy group of formula Q--OH with a silanehaving the general chemical formula R'₃ Si--A--NHY, where A is asdefined above, R' represents an alkoxy group and Y represents hydrogen,alkyl or aryl groups, or a group having the formula X--CO₃ H to form anintermediate of formula Q--O--Si--A--NHY Stage (ii) Reacting theintermediate from Stage (i) with a compound of formula Z--X--D orZZ'--X'--D where X and X' are as defined above, Z and Z' represent anoxy- or halogen-containing leaving group and D represents a carboxylicacid group or a functionality capable of conversion thereto to form anintermediate of formula ##STR15## and Stage (iii) Reacting theintermediate from Stage (ii) with hydrogen peroxide in the presence of astrong acid selected from the group consisting of sulphuric acid, asulphonic acid, and phosphoric acid thereby producing aninorganic-supported peracid having one of the general formulae describedabove.
 16. The process according to claim 15, wherein stage (i) iscarried out in a solvent which is selected from the group consisting oftoluene, hydrocarbons, halocarbons and ethers.
 17. The process accordingto claim 15, wherein stage (ii) is carried out in acetic acid solvent.18. The process according to claim 18, wherein in stage (iii), thestrong acid is selected from the group comprising sulphuric acid,methanesulphonic acid, phosphoric acid and mixtures thereof.
 19. Theprocess according to claim 15, wherein stage (iii) is carried out at atemperature of up to about 40° C.
 20. The process according to claim 15,wherein A comprises a linear alkylene group having from 1 to 10 carbonatoms.
 21. The process according to claim 15, wherein A comprises alinear alkylene group having from 2 to 5 carbon atoms.
 22. A processaccording to claim 15, wherein X comprises a linear alkylene grouphaving up to 18 carbon atoms.
 23. A process according to claim 22,wherein X comprises a linear alkylene group having from 10 to 14 carbonatoms.
 24. A process according to claim 15, wherein N--X comprises anamino alkylene or amino arylene group and N X' comprises a cyclic imidoarylene group.
 25. A process according to claim 24, wherein ##STR16##comprises a phthalimido group.
 26. A process according to claim 15,wherein Q comprises an aluminum, silicon or aluminosilicate basedinorganic support.
 27. A process according to claim 15, wherein Qcomprises silica gel or a natural or synthetic clay.
 28. A processaccording to claim 15, wherein the inorganic support has a surface areain the range of from about 50 m² /g to about 1000 m² /g.
 29. A processaccording to claim 15, wherein the inorganic support has a surface areain the range of from about 200 m² /g to about 800 m² /g.
 30. A processaccording to claim 15, wherein the inorganic support comprises silicagel having a surface area in the range of 250 to 350 m² /g, A is alinear (CH₂)₃ group and N is bonded to two carbonyl groups fused with abenzene ring to form a phthalimido group, the peracid group being bondeddirectly to the benzene ring in the meta position relative to onecarbonyl group and in the para position relative to the other carbonylto produce an inorganic-supported peracid having the formula: ##STR17##31. A process according to claim 15 wherein X or X' is oxo-substitutedat the alpha position relative to the N.
 32. The process according toclaim 15 or 26 wherein X or X' separate the peracid group CO₃ H from Nby from 2 to 6 carbon atoms.